I'm in the process of building a Uds and hope to cold smoke bacon, cheese. etc. I'm planning on using an amnps as the cold smoke generator. Can I add additional racks closer to the charcoal basket for additional room during a cold smoke? Or would I have some problems?

You'll find out once the cheese melts lol..
I always run ice bricks in the smoker to keep temp down..
Also look at the letter box method. That way smoke is at ambient temp before it enters the smoker..